A Silver‐Copper Alloy as an Oxygen Reduction Electrocatalyst for an Advanced Zinc‐Air Battery

Abstract

A highly efficient Ag‐Cu electrocatalyst is synthesized by the electrodeposition method and characterized with respect to its catalytic activity in the oxygen reduction reaction (ORR) and its tolerance to carbonate ions in a zinc‐air battery. Cyclic voltammetry and rotating‐disk electrode analyses suggest that the Ag50Cu50 electrocatalyst is 2.5 times more catalytically active in the ORR than a pure Ag catalyst and catalyzes the ORR through a four‐electron pathway. Field‐emission TEM characterization shows that the surface‐roughened Ag‐Cu electrocatalyst comprises small nanoplatelets with diameters of 40–50 nm. Cu atoms are partially alloyed in Ag lattices in these nanoplatelets. The Ag‐Cu electrocatalysts are assembled into the primary and secondary zinc‐air batteries as carbon‐free and binder‐free catalyst layers. The open circuit voltage and the discharge voltage of the primary zinc‐air battery at 20 mA cm−2 are 1.49 and 1.17 V, respectively. The round‐trip efficiency and increased polarization of the rechargeable zinc‐air battery are 56.4 and 0.2 %, respectively, after 100 cycles at 20 mA cm−2. The Ag‐Cu electrocatalyst shows good catalytic activity in the oxygen evolution reaction in an alkaline battery and good tolerance of carbonate ions on the cathode side.

Gold–Copper Aerogels with Intriguing Surface Electronic Modulation as Highly Active and Stable Electrocatalysts for Oxygen Reduction and Borohydride Oxidation

“…[31] Close inspection shows that the Au 4f peaks shift to slightly higherb inding energiesw ith an increase in the Cu content;t his is indicative of the gradual incorporation of Cu atomsi nA ua nd the formation of uniform AuCu bimetallic nanoalloys. [24,32] It can be seen that only at race amount of Cu 2 + is observed in the Cu 2p spectrum; this suggestsa ne ffective stabilization effect of Au on Cu andf urther confirms the XRD results. [24,32] It can be seen that only at race amount of Cu 2 + is observed in the Cu 2p spectrum; this suggestsa ne ffective stabilization effect of Au on Cu andf urther confirms the XRD results.…”

“…In the Cu 2p CL spectrum ( Figure 8b), the bindinge nergy values of the Cu 2p 3/2 and Cu 2p 1/2 CLs at 932.6 and 952.3 eV,r espectively,a re consistent with those reported for metallic Cu. [24,32] It can be seen that only at race amount of Cu 2 + is observed in the Cu 2p spectrum; this suggestsa ne ffective stabilization effect of Au on Cu andf urther confirms the XRD results. The d-bandc enter (e d )v alues of the different catalysts were then further investigated by surface valence band spectra (VBS) in Figure 9.…”

“…Remarkably,t he SA and MA achieved in the Au 52 Cu 48 aerogels are the highest among Au-Cus ystemsi nr ecently reported studies (Table S3). [24] Furthermore, the electron transfer number (n)o ft he Au 52 Cu 48 aerogels catalyst for the ORRw as calculated to be approximately 4f rom the slopes of the Koutecky-Levich plots (inset in Figure 3d); this suggests af our-electron pathway towards the ORR and complete reduction of O 2 to HO À on the electrode surfacei na lkaline media, which is superior to the two-electron peroxide generation process catalyzedb yp ure Au (n = 2.4) ( Figures S6 and S7). The limiting currenti ncreases with an increase in the rotation speed, demonstratingt hat the ORR catalytic activity of the Au 52 Cu 48 aerogelsi sc ontrolled by the diffusion of O 2 .…”

“…The limiting currenti ncreases with an increase in the rotation speed, demonstratingt hat the ORR catalytic activity of the Au 52 Cu 48 aerogelsi sc ontrolled by the diffusion of O 2 . [24] Furthermore, the electron transfer number (n)o ft he Au 52 Cu 48 aerogels catalyst for the ORRw as calculated to be approximately 4f rom the slopes of the Koutecky-Levich plots (inset in Figure 3d); this suggests af our-electron pathway towards the ORR and complete reduction of O 2 to HO À on the electrode surfacei na lkaline media, which is superior to the two-electron peroxide generation process catalyzedb yp ure Au (n = 2.4) ( Figures S6 and S7).…”

Cauliflower‐Like Hierarchical Porous Nickel/Nickel Ferrite/Carbon Composite as Superior Bifunctional Catalyst for Lithium‐Air Battery

“…Development of high‐performance electrochemical energy conversion and storage devices such as fuel cell, battery, ultracapacitor, supercapattery, metal‐air batteries, and their hybrids is indispensable for the consumer electronics as well as effective utilization of renewable energy sources, especially solar photovoltaics. While the fuel cells convert chemical into electrical energy as long as the fuel and the reactant are supplied, the metal‐air batteries are rechargeable or refuelable. Among the various metal‐air batteries which are under development, Li‐Air and Zn‐Air batteries are attractive due to their high theoretical capacity, excellent energy density, simplicity, low cost and non‐toxic.…”